<!DOCTYPE html>
<html>
<head>
  <title>Kitten Monitor</title>
<meta name="description" content="A variation of a monitoring diagram where the objects of interest maintain a constant size while the user zooms in and out on the map." />
  <!-- Copyright 1998-2016 by Northwoods Software Corporation. -->
  <meta charset="UTF-8">
  <script src="go.js"></script>
  <link href="../assets/css/goSamples.css" rel="stylesheet" type="text/css" />  <!-- you don't need to use this -->
  <script src="goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->
  <script id="code">
    function init() {
      if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this
      var $ = go.GraphObject.make;  // for conciseness in defining templates

      myDiagram =
        $(go.Diagram, "myDiagramDiv",
          {
            initialContentAlignment: go.Spot.TopLeft,
            isReadOnly: true,  // allow selection but not moving or copying or deleting
            "toolManager.hoverDelay": 100,  // how quickly tooltips are shown
            "toolManager.mouseWheelBehavior": go.ToolManager.WheelZoom  // mouse wheel zooms instead of scrolls
          });

      // the background image, a floor plan
      myDiagram.add(
        $(go.Part,  // this Part is not bound to any model data
          { layerName: "Background", position: new go.Point(0, 0),
            selectable: false, pickable: false },
          $(go.Picture, "https://upload.wikimedia.org/wikipedia/commons/9/9a/Sample_Floorplan.jpg")
        ));

      // the template for each kitten, for now just a colored circle
      myDiagram.nodeTemplate =
        $(go.Node,
          new go.Binding("location", "loc"),  // specified by data
          { locationSpot: go.Spot.Center },   // at center of node
          $(go.Shape, "Circle",
            { width: 12, height: 12, stroke: null },
            new go.Binding("fill", "color")),  // also specified by data
          { // this tooltip shows the name and picture of the kitten
            toolTip:
              $(go.Adornment, "Auto",
                $(go.Shape, { fill: "lightyellow" }),
                $(go.Panel, "Vertical",
                  $(go.Picture,
                    new go.Binding("source", "src", function(s) { return "images/" + s + ".png"; })),
                  $(go.TextBlock, { margin: 3 },
                    new go.Binding("text", "key"))
                )
              )  // end Adornment
          }
        );

      // pretend there are four kittens
      myDiagram.model.nodeDataArray = [
        { key: "Alonzo", src: "50x40", loc: new go.Point(220, 130), color: "blue" },
        { key: "Coricopat", src: "55x55", loc: new go.Point(420, 250), color: "green" },
        { key: "Garfield", src: "60x90", loc: new go.Point(640, 450), color: "red" },
        { key: "Demeter", src: "80x50", loc: new go.Point(140, 350), color: "purple" }
      ];

      // This code keeps all nodes at a constant size in the viewport,
      // by adjusting for any scaling done by zooming in or out.
      // This code ignores simple Parts;
      // Links will automatically be rerouted as Nodes change size.
      var origscale = NaN;
      var oldscale = NaN;
      myDiagram.addDiagramListener("InitialLayoutCompleted", function(e) { origscale = oldscale = myDiagram.scale; });
      myDiagram.addDiagramListener("ViewportBoundsChanged", function(e) {
        if (isNaN(origscale)) return;
        var newscale = myDiagram.scale;
        if (oldscale === newscale) return;  // optimization: don't scale Nodes when just scrolling/panning
        oldscale = newscale; 
        myDiagram.skipsUndoManager = true;
        myDiagram.startTransaction("scale Nodes");
        myDiagram.nodes.each(function(node) {
            node.scale = origscale / newscale;
          });
        myDiagram.commitTransaction("scale Nodes");
        myDiagram.skipsUndoManager = false;
      });

      // simulate some real-time position monitoring, once every 2 seconds
      function randomMovement() {
        var model = myDiagram.model;
        model.startTransaction("update locations");
        var arr = model.nodeDataArray;
        var picture = myDiagram.parts.first();
        for (var i = 0; i < arr.length; i++) {
          var data = arr[i];
          var pt = data.loc;
          var x = pt.x + 20 * Math.random() - 10;
          var y = pt.y + 20 * Math.random() - 10;
          // make sure the kittens stay inside the house
          var b = picture.actualBounds;
          if (x < b.x || x > b.right) x = pt.x;
          if (y < b.y || y > b.bottom) y = pt.y;
          model.setDataProperty(data, "loc", new go.Point(x, y));
        }
        model.commitTransaction("update locations");
      }
      function loop() {
        setTimeout(function() { randomMovement(); loop(); }, 2000);
      }
      loop();  // start the simulation
    }
  </script>
</head>
<body onload="init()">
<div id="sample">
  <h3>Kitten Monitor with constant size tokens representing kittens</h3>
  <div id="myDiagramDiv" style="border: solid 1px black; width:100%; height:600px"></div>
  <p>The tooltip for each kitten shows its name and photo.</p>
  <p>When you zoom in or out the effective size of each Node is kept constant by changing its <a>GraphObject.scale</a>.</p>
</div>
</body>
</html>